although you might be beat by two pair, set or straight you have 3 outs to straight+ 9 outs to flush if you´re behind and with tptk you might be ahead on the turn.
So I think c/rai is fine play on the turn with your equity.
If you think players would call your shove with worse hands you can also shove turn for value

I think that folding turn is the correct play because the flop is really dangerous for 4 players in the pot and by them calling you PF 6bb raise i would be most certain that at least one of them has AJ, KQ, TT,QQ,KK and you're behind all of those hands so you're almost never ahead on the tur after they all called the flop. I would only count my flush outs on the turn and make my tptk only a drawing hand which almost never in this spot has a showdown value if not improved. I think you have about 10-11 outs in this spot assuming he's ahead. I'm not sure if the odds are good enough on the turn but I think they are so it was a good call. I would never c/r all-in on the turn, just call because if MP3 shoves and BU calls that almost always means that BU has something far more better that tptk so there is no point in getting all of your chips in the middle.